1. Field of the Invention
This invention relates to the sampling of water for microbiological quality determinations, and particularly to a method for maintaining the integrity and validity for an extended period of time of a sample of water drawn for the purposes of microbiological testing by a laboratory.
Certain microbiological tests conducted upon water samples have required testing due to the possible loss or change of microbiological contaminants after collection of the samples. For various reasons, such as convenience, it has not always been possible to perform all necessary microbiological testing immediately upon the collection of the water samples. In such circumstances, the Environmental Protection Agency (EPA), which is the responsible governmental regulatory agency, has set forth requirements to stabilize such water samples to ensure accuracy in assessing the contamination from microbiological agents.
Shipping the test samples to the testing site in the past has proved unfeasible, since EPA requires certain samples for certain microbiological contamination determinations be tested within a limited time period. While the EPA has specified procedures for allowing a lengthening of the normal 30-hour "holding" time within which normal microbiological testing must occur to be valid, such procedures have not been readily accessible to the general public and have also been cumbersome and infrequently employed by laboratories, due to the inconvenience of the available and accepted methodologies.
2. Description of the Prior Art
In the past, samples to be later tested required immediate chilling of the sample at the sampling site and maintenance of the sample at 4 degrees centigrade during the immediate transportation to the laboratory. This manner of sample testing has the expense of rapid and special transportation and of the equipment for constant-temperature maintenance of samples while en route to the laboratories. Moreover, the samples do not always arrive in a usable condition, e.g., the means for chilling may be inadequate or the transportation may fail to deliver on time.
The other manner of testing, that is, on-site sampling and testing by laboratory personnel, also involves increased expense. These expenses involve both the time in traveling to and from the site and the maintenance of appropriate mobile apparatus for use by the laboratory personnel.
There has, therefore, been a need to develop a sampling device for collection of water sample for microbiological testing, whereby lay persons may receive sampling devices shipped by common carrier, collect the samples in the devices, and then ship the sample devices to central laboratories by common carrier for testing.
It is thus object of the invention to provide a simple and relatively inexpensive sampling device which permits inexperienced persons to take water samples, while permitting a substantial increase in the time period in which to make valid tests on such samples. It is another object to maintain laboratory samples for transportation to a testing site at a central location remote from the source of the samples.
It is a further object of the invention to provide a physical device which can be mailed or otherwise be shipped to and from a remote sampling site by common carrier and forwarded therefrom with water samples to a central laboratory.
The present invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.